A conventional spectacle lens has a mark for indicating its product name and manufacturer, a mark as a reference for fitting to a spectacle frame, a mark for identifying a product in a manufacturing process and so forth. In particular, the mark for identifying a manufacturer is not used only for the identification purpose but also for offering quality assurance of the product by the manufacturer.
These marks are engraved using a needle made of hard material such as diamond (diamond pen) as disclosed in JP-A-2000-153698 (pages 1 through 3), or formed by focused laser beam at the inside or surface of a spectacle lens as described in Japanese Patent Nos. 2,810,151 (pages 1 and 2) and 3,081,395 (pages 1 through 3).
In marking by means of the diamond pen or the like, the surface is slightly engraved and scratched to provide a marking. As a result, a problem known as peel of coating may arise in which hard coating and anti-reflection coating peel off from the area of the marking scratch.
Additionally, the mark for indicating a product name and a manufacturer and the mark as a reference for fitting to a spectacle frame after shipment remain on the surface of the spectacle lens after the spectacle lens is fitted to the frame. Thus, the mark formed in an area which is finally fitted to a spectacle frame is required to have appearance which does not obscure the field of view and be visible under certain conditions.
However, for forming a mark which does not obscure the wearer's field of view, it is necessary to decrease the output of the laser beam, reduce the engraving load on the diamond pen, make the mark smaller in size, form a mark having a configuration not easily visible or take other measures. Thus, only such a mark is formed which cannot be easily observed due to its low visibility when visual recognition of the mark is needed.
It is a first object of the present invention to provide a manufacturing method of a spectacle lens, marking apparatus, and a spectacle lens having a mark capable of forming a mark which does not obscure a wearer's view and yet can be easily observed as necessary without scratching hard coating and anti-reflection coating, unlike a conventional marking method.
Additionally, in forming a mark in a spectacle lens, it is required to provide a mark accurately in such a position where the mark does not obscure a glass wearer's view or at a position desired by a glass wearer as described above.
It is a second object of the invention to provide a manufacturing method of a spectacle lens, a spectacle lens and a marking system capable of forming a mark precisely at a desired position inside a spectacle lens.